KG isn't 7'1" (he just looks taller than 6'11" because of his wingspan and his jumping ability). For the longest time, he was listed as 7'0" but they finally got his correct measurements. Most NBA players are listed taller than they really are but NEVER shorter.
Here are some players that are listed taller than they really are ...
Elton Brand
Listed: 6'9"
Real height: 6'6" (I saw him play and he stood no taller than Marko Jaric and Corey Maggette)
Shaq O'Neal
Listed: 7'1"
Real height: 6'11" (My friend told me this and I didn't believe him. I watched the Christmas game and I saw him standing next to Kelvin Cato. They were the same height!)
Charles Barkley
Listed: 6'6"
Real height: 6'4"
Hakeem Olajuwon
Listed: 7'0"
Real height: 6'10"
Larry Johnson
Listed: 6'6"
Real height: 6'4"
These are just the ones I'm aware of ... I think most of the 7 footers are really 6'11" (i.e. Elden Campbell. When he played for the Lakers, he was listed as 6'11" as a PF. Now that he primarily plays center, he is always listed as 7'0").
Also, did you guys notice Kobe Bryant is no longer listed as 6'7"? He is back to his real height ... 6'6" (the height he was listed as when he came into the league).